Obscured Twin Moons
by Desaeta
Summary: When the worlds of Mobius and the Underground begin colliding, only twelve brave warriors (including four bad fan characters) can put an end to the culprits' evil scheme and save both dimensions.


**Author's Notes: Hello, and welcome to Obscured Twin Moons. I'll probably start referring to it as OTM. This is a crossover Sonic and Undertale fanfiction featuring bad fan characters and tropes. Please note that all fan characters are original and if our characters have the same names, it doesn't mean that I'm stealing your character. It just means that I'm not creative and bad at thinking of names. Also, please feel free to write mean reviews. It lets me know that you're paying attention to the bad tropes that I fit in. With that said, have fun reading this story. You can decide whether you like it or not.**

Planet Mobius. A world known for its green grasses, sparkling oceans, and steel fortresses. The home of the fastest creature alive, Sonic the Hedgehog, and his sworn enemy, Dr. Eggman. It has been four months since Eggman's last attack on Mobius, where he was foiled once again. Even so, peace has fled from the heroes once again in favor of a clash between bitter rivals.

"Oof-!" Sonic the Hedgehog grunted, planting his shoes into the ground and skidding backwards. He placed a white-gloved hand on a tan shoulder, his blue head hanging low. "Shadow…! What's goin' on?"

The black hedgehog simply shook his head, his red-streaked spines shuddering slightly as a cold wind blew across the moonlit plains. His red eyes locked on his rival, he walked forwards slowly. "Sonic. The Chaos Emerald. Give it to me, now."

"Heh. So that's what this is about." Sonic lifted his head, his green eyes gleaming with a newfound amusement. "You want the Emerald? You'll have to take it from me."

"So, that's your choice." Shadow held a gloved hand up, a small orange ball of light appearing. "I suppose I have no option but to pry it from your dead body, then. Chaos Spear!" He threw his arm forwards, a sharp beam of orange energy soaring straight towards Sonic. A brilliant white light shone throughout the area as it advanced towards the blue hedgehog…

"Is that it?" a voice called from the light. Shadow squinted. That was Sonic's voice. But there was no way… Sonic had already been weakened. There was no way he could have dodged that in time.

"Forgetting about something?" another voice taunted. That was…! The black hedgehog's eyes widened. As the light died down, he saw a green barrier flashing out of existence. Within it was a yellow-orange fox, his two tails tipped with white.

"Damn it…" Shadow muttered.

"Thanks, Tails," Sonic sighed, standing back up. "You came just in time. Mind helping me out a little with this guy?"

"Not at all," Tails replied, a red arm-mounted cannon appearing from thin air.

Shadow grunted. He hadn't planned for Tails to jump in. Although the fox wasn't very strong on his own, he would be a good distraction to cover Sonic's attacks. And besides, the two had some powerful combination attacks. He'd have to get creative if he wanted to win the Emerald.

"Guh-!" he spat as a large orb of energy struck him. He hadn't been paying enough attention, and Tails had gotten a hit in. This would be the only time, though. As soon as the orb exploded, Shadow planted his hands in the ground and flipped backwards, landing on his feet. He jumped to the side, narrowly avoiding a Spin Dash from Sonic, before hurling a Chaos Spear at Tails. The fox jumped into the air and spun his tails around, flying above it as it neared him. Shadow glanced to the side and saw Sonic leaping into the air. He was preparing a Homing Attack, Shadow realized; the two had gotten in too many conflicts for him to not realize that motion. There was only one way to counter that. Shadow, too, jumped into the air and took aim at Sonic's spinning form. Putting all of his energy in the blue hedgehog's direction, he shot forwards at the same time that Sonic did the same. The two curled-up hedgehogs bounced off of each other, flying backwards without much damage to either. As soon as Shadow hit the ground, though, a sharp pain hit his side, sending him flying. He turned his head, seeing Tails finishing a tail swipe. How ironic… he'd figured that Tails would be the distraction, not Sonic.

"Had enough?" Sonic asked. "Or do we need to teach you a lesson?"

"Rrgh…" Shadow groaned, climbing to a knee. He had to get that Emerald. Sonic couldn't be trusted to keep it away from Eggman any more than Knuckles could be trusted to protect the Master Emerald. He was running out of options, and he was getting desperate. A single hand grabbed at one of the Inhibitor Rings on his wrists. It would cost him everything, and it would be risky, but it was the only chance he had at this point.

"There you are," a voice called from behind Shadow. The black hedgehog turned his head slightly. A figure was approaching, one that he'd seen before. Their meeting was inevitable, but Shadow had figured that it wouldn't be so soon.

"Shadewood," Shadow groaned. "I was wondering whether I'd ever see you again."

The dark grey wolf laughed darkly, his red eyes focused on Sonic and Tails. "So, you're the two heroes. I've been dying to meet you." His brown trenchcoat shifted as he grabbed his black fedora with a gloved left hand. "I heard you have a Chaos Emerald."

"What about it?" Sonic asked, looking at the wolf suspiciously. He'd never seen this one before, but he looked dangerous.

Shadewood reached inside a pocket with his other hand and pulled out a pistol. He pointed the barrel at the hedgehog's head. "I'll be taking it."

Wasting no time, Tails put up a shield just as Shadewood pulled the trigger. "Sonic!" he shouted as the bullet reflected off of the shield. "Are you all right?"

"Yeah," the blue hedgehog replied. "Thanks, Tails."

"Were you actually expecting to get him so easily?" Shadow grunted, standing up slowly and looking at Shadewood.

"Of course not. I'm not an idiot. But it seems like you need this Emerald just as much as I do." Shadewood glanced over at Shadow.

"I'm not cooperating with you," the black hedgehog spat. "Get out of here and let me fight my own battles. I work alone."

"What a shame. And I was even planning on lending you this." The wolf held out a red Chaos Emerald for Shadow to see.

"A Chaos Emerald…!" Shadow gasped, his eyes widening. "Where the hell did you get that?"

"Swallow your pride and fight with me. I might tell you if we win."

The black hedgehog closed his eyes for a second before sighing. "Fine. Just give me the Emerald."

"Don't do anything stupid," Shadewood chuckled, tossing the jewel at Shadow. Catching it in a glove, Shadow nodded slowly.

"So, it's two versus two now." Sonic grinned, pulling out a green Chaos Emerald. "Alright, I'm up for that!"

"We're not gonna lose!" Tails shouted.

"You're finished," Shadow spat.

"You messed with the wrong guy," Shadewood taunted.

All four tensed up for a moment, their eyes glancing between one another. In the blink of an eye, they were in the center, a flurry of attacks being exchanged between them.

In the distance, a pair looked upon the duel, both uncomfortable.

"Sonic…" a pink hedgehog moaned. her hands against her red dress. "I hope he'll be alright."

"Sonic's a tough guy, Amy," the girl beside her replied. Her golden fur shone in the moonlight, mostly covered by her pink dress and red heels. She had a rabbit-like pair of ears and nine bushy fox tails.

"I know, Lotusleaf," Amy sighed. "I'm just… I just get scared when he goes out and starts fighting like this."

The kitsune and rabbit fusion nodded. "I feel the same way about Shadewood. But I'm sure they'll be all right. And besides…" Lotusleaf held out a large golden ring surging with life energy. "We have a few Rings of Life. We can revive them, remember?"

"What if they just start fighting again?" Amy asked. "Or what if the rings don't work? Or what if they're hurt too badly to be revived? Or-"

"We'll worry about that if it happens." Lotusleaf looked at Amy sternly. "For now, we need to stay calm. This is their battle, Amy."

"…If you say so." The pink hedgehog fell down, sitting on the ground. "Lotusleaf, why are you supporting me? Doesn't Shadewood hate Sonic?"

Lotusleaf, remembering her boyfriend, nodded. "Yes. But that doesn't mean I can't help somebody out, does it?"

"I guess not." Amy turned back to the battle. "Do you know what they need the Emerald for? Shadow and Shadewood, I mean."

"I'm not sure about Shadow," Lotusleaf explained, "but Shadewood… well, he wants to use it to power a machine. He already has two Emeralds, but everybody thinks that Eggman has six, so nobody knows that he's secretly been keeping an old power suit that Eggman threw away. He's been powering it up with the Emeralds, and he thinks that this one will give it enough strength to finally start moving."

"A power suit? Why would he need that?"

"I'm not sure. I've tried asking, but he just ignores me. Maybe, if he gets the Emerald, he'll tell me." Lotusleaf sighed. "We've been together for months, but he still hides so much from me."

"Lotusleaf! Look!" Amy shouted suddenly. Lotusleaf gasped and turned towards the battlefield. Sonic and Shadow both held out a Chaos Emerald.

"No-!" Lotusleaf shouted. "Are they going to…?!"

Sonic grunted, the pain in his side growing. He and Tails were in bad shape, but at least the other two weren't doing much better. He knew Shadow wouldn't use Chaos Control as long as he held the Emerald out; if they both used it at the same time, the results would be catastrophic.

Shadow narrowed his eyes. Sonic was too much of a good guy. He wouldn't purposefully try and use Chaos Control at the same time as he did. But on accident? Maybe. Shadow couldn't take any chances, unless he wanted to be dragged into a different timeline. The only way he could think to end this would also hurt Shadewood, and it would hurt him a lot. But Shadow didn't mind.

"Oof-!" Shadow heard. He looked over at his opponents. Shadewood had somehow gotten to the other side and knocked Tails out. Sonic spun around just in time to dodge another kick from Shadewood. This was his chance.

"Chaos Control!" the black hedgehog shouted. He saw Shadewood and Sonic's running gradually slow until they had stopped completely. Time had frozen. Shadow walked up to Sonic, pausing for a moment before bringing both fists down upon the hedgehog's head. That would knock him out. He then turned to Shadewood. What about this one…? Shadow shook his head; he wasn't going to go there yet. Decided, he held out his arm and the Chaos Emerald, allowing time to return to normal.

"Ugh…" Sonic mumbled, falling slowly to the ground from the earlier impact. He hit the grass softly, his eyes half-open. "I… won't let you… take… it…"

"Sonic, you've lost." Shadow looked at the blue hedgehog intensely. "Give me the Emerald and we won't have to take this any further."

Sonic looked up at Shadow and shook his head. With the last of his energy, he pulled out the jewel and threw it as far away as he could. "Ngh… now neither of us can use it." Sonic smiled softly, closing his eyes. "You beat us in combat, but in the end, it looks like you lost."

Shadow narrowed his eyes and sighed. "I'll just have to get it, then."

"About that."

The black hedgehog spun around to see a gloved fist rushing towards his face. The punch made impact, causing Shadow to stagger before falling to the ground. He looked up to see Shadewood standing above him. "Rrgh…" he grunted.

"I assumed you'd know that our partnership ended as soon as those two were down. I'll be taking the Emerald." Shadewood, his face still tight, turned away.

Shadow winced. That punch hurt, and unless he could delay Shadewood, he wasn't going to get the Emerald. He didn't want to be forced into pulling this card, but he was desperate. "So… I guess you're just discarding your own brother, huh."

Shadewood paused. "What… are you talking about?" he demanded.

"Did you think that they just got the Ultimate Life Form perfect after the Biolizard prototype?" Shadow asked. "Of course they didn't. You were the penultimate attempt, Shadewood."

"You're bluffing." Shadewood shook his head. "You're lying. I have no connection to you."

"Believe what you will. I'm only telling you the truth."

"I remember my parents dying. Did I just imagine that or something?"

"You were taken in by adoptive parents, you fool!"

"…No," Shadewood mumbled. "It's not true. I- Ugh!" The wolf grunted, falling to the ground. "Wha…?!" He turned his head to see Shadow, returning to a standing position from a kick. "You…!"

"Don't get back up," Shadow muttered. "I'll end this quickly."

"Stop!" a voice shouted. Shadow turned his head to see a golden creature running towards him.

"Lotusleaf! No!" another called. This was one Shadow recognized. Amy Rose.

"Get away from him!" Lotusleaf yelled, just as Amy grabbed one of her arms.

"Don't do this, Lotusleaf!" Amy retorted. "He'll be okay!"

"Let me go! I need to help him!"

"I don't want to lose you!"

"Get off of me!"

"Lotusleaf, cut it out!"

"Amy, stop! Let me GO!"

"I don't want to lose the only family I have left!" Amy finally screamed. Lotusleaf suddenly stopped, turning towards the pink hedgehog.

"Wh-what do you mean?" she mumbled.

"I've been looking for you for so long," Amy replied, tearing up. "They said that it was impossible, that you couldn't be the same Lotusleaf that I grew up with. My adoptive sister… but I knew it was you." The pink hedgehog was in tears. "I was scared that you would get hurt… Don't go, Lotusleaf."

Lotusleaf closed her eyes, unable to move. She collapsed to the ground, her breathing ragged. Amy could do little to help but hold her, crying.

Shadow shook his head. More drama… At least they were distracted. Slowly, he pulled a pistol out, pointing it at Shadewood. "I'm sorry, but I need the Emerald. Don't move-" Shadow's words were interrupted with a sudden pain from behind him that sent him flying. He turned around. Sonic…? But he had been knocked out…

"Cut it out, Shadow!" Sonic yelled. "Just give him the Emerald. He'll let you have it once he's done. Right, Shadewood?"

The grey wolf simply climbed to his feet, grunted, and turned away. "Let him have it."

* * *

"Hmm… This seems bad." The figure paced around the small room, checking once again to make sure he was correct. Sure enough, he sensed it again. A corruption in space-time that was rapidly growing. If this kept up, he would be dragged in – but more importantly, the others would be in danger. "I need to warn them, at least."

"Hey, bro. Something wrong?" a voice asked. The figure turned to the doorway, seeing his sister standing still.

"We need to gather everybody up for a talk."

"A talk? Last time you wanted everybody together for a talk, you-"

"No, I'm not planning on unveiling my greatest joke yet. That's still too good for now. It's something serious this time."

"Well, if you say so. Do you want me to go get everybody?"

"Yeah. They'll probably believe you more, anyway."

"Okay. Where should I tell them to meet?"

"Is the door to… her old house… still open?"

"Her old house… Oh, yeah. I think so. But are you sure? Some people don't exactly have good memories of that place."

"I know, but the only other safe meeting place I can think of is even worse."

"Oh. Got it, then. I'll go get them. Just sit tight, okay?" With that, the girl left the room, leaving the remaining figure alone with his thoughts.

"…I just hope it's not that kid," he sighed. "They're too strong for any of us to take on alone." The figure sighed, dusting off his short blue hoodie. "Well, better get going. Don't want to keep the rest waiting."


End file.
